The present invention relates to a method of manufacturing products of plastic to which a filler preferably of wood material has been added to a high degree more particularly, the invention relates to such a method in which a thermosetting or otherwise solidifying plastic compound, aggregated with finely divided filling material, so that a mixture is obtained, is introduced into a mould, in which it is subjected to pressure in order to shape the desired product. The invention also relates to apparatus provided for carrying out the above-mentioned method.
Plastic material has turned out not to be suitable for the production of solid or thickwalled articles of large dimensions, by way of example certain products for the building industry, as window frames, window sashes, doors, door frames and moreover objects of interior decoration, due to the high price per cubic unit compared with conventional materials such as wood and particle board. However, it would be desirable in connection with such products to be able to exploit the excellent characteristics of plastics from a maintenance and appearance point of view and because of its good shaping quality, so that casting methods might be substituted for the hitherto common and more expensive chip cutting machining methods.
As is the case by production of particle boards, a solution of the problem involves letting the plastic material comprise a relatively small proportion of the articles, the balance comprising fillers like sawdust, wood-chips, cutter shavings, coarse woodpulp and/or the like. However, it has turned out that a mixture containing an adequate amount of filling material in order to satisfy a sufficiently low price is not ductile enough to permit the use of conventional die casting methods for the technique of plastics.